I've been using it since it was announced and I haven't had any problems.
To the contrary, it seems like a very quick and stable app. My fans aren't noisy, my CPU isn't overloaded, etc. It uses Spotlight, yes, but it enhances it. The searches are quicker than Spotlight, and it searches Gmail which is reason enough for me to use it. Google Desktop is better on the Mac than on the PC, so kudos to the Mac Development team @ Google.